The present invention refers to improvements in hydro-pneumatic suspensions for road vehicles, by means of which smoother operation of the vehicles is achieved. Additionally, greater safety is achieved because of the improved recovery of stability when the vehicle tends to lean to one side on a curve or when it swerves sharply, due to centrifugal force. This is in contrast to existing systems which `give` to the weight of the load and to the centrifugal force itself, thereby endangering the lives of the passengers and the unit itself.
The tendency on the art of the automotive engineers in the designing of suspensions for buses and trucks, has been to obtain a smoother and more comfortable running of the vehicle over the unevenness of the road.
The designs that have been most used commercially have been the following:
1. Suspension with a fixed axle. PA1 2. Suspension with a fixed axle with leaf springs. PA1 3. Suspension with shock absorbers and helical springs. PA1 4. Shock absorber suspension, helical springs and twin axles. PA1 5. Suspension with rigid axle and leaf springs of variable ratio. PA1 6. Suspension with a rigid axle and radial leaf springs with a progressive ratio. PA1 7. Suspension with leaf springs and air bags. PA1 8. Suspensions with torque rods. PA1 9. Air suspensions. PA1 10. Hydro-pneumatic suspensions. PA1 1. Control of vertical movement. PA1 2. Control of angular movement between frame and axle. PA1 3. Control of lateral displacement. PA1 4. Control of rotation from brake torque. PA1 (a) Greater comfort for the driver and passengers. PA1 (b) More load capacity. PA1 (c) The design height of the suspension does not vary, maintaining the vehicle with or without load at the same height. PA1 (d) The useful life of the vehicle is lengthened because the fatigue forces are diminished. PA1 (e) Greater safety from the fast recovery of stability of the vehicle. PA1 (f) Lengthening the useful life of the tires and maintaining the vehicle stable and in alignment. PA1 (g) Minimizing the effect of vibrations which originate from changes in the asphalt layers.
By means of innovations these systems have been able to reduce the amplitude of the vertical vibrations, which in the spring suspensions vary between 179 and 655 (cpm); and which in air and hydro-pneumatic suspensions have a vibration range of 138 to 197 (cmp). This is essentially constant.
The hydro-pneumatic suspension of the present invention, satisfies the following parameters of design, operation and control:
The hydro-pneumatic suspension principle has been patented in various countries for use in automotive vehicles, each one with different component design and installation geometry.
In U.S. Pat. No. 3,736,001, the use of one hydro-pneumatic cylinder per wheel is specified. The cylinder is anchored to the chassis and the load axle by means of a ball and socket arm and pivoted support. In the present invention, two hydro-pneumatic cylinders of special design are used per wheel to diminish the operating forces and fatigue by 50%. In this way a greater load capacity and longer life of the system is obtained.
Reference is made to my Mexican Pat. No. 111487 which also discloses the use of a hydro-pneumatic shock absorber suspension. The disclosed shock absorber simplifies the system in general, with which a considerable reduction of parts is obtained and with the consequent reduction in the cost of manufacture.